cvs commit: src/sys/boot/i386/loader main.c
jhb at freebsd.org
Tue Dec 20 07:29:03 PST 2005
On Monday 19 December 2005 11:32 pm, Maxim Sobolev wrote:
> John Baldwin wrote:
> > On Monday 19 December 2005 01:32 pm, Maxim Sobolev wrote:
> >> John Baldwin wrote:
> >>> On Monday 19 December 2005 04:26 am, Maxim Sobolev wrote:
> >>>> sobomax 2005-12-19 09:26:42 UTC
> >>>> FreeBSD src repository
> >>>> Modified files:
> >>>> sys/boot/i386/loader main.c
> >>>> Log:
> >>>> If LOADER_BZIP2_SUPPORT is defined allocate heap in the 1MB-4MB
> >>>> range to provide enough room for decompression (up to 2.5MB is
> >>>> necessary). This should be safe to do since we load i386 kernels after
> >>>> 8MB mark now, so that 16MB is the minimum amount of RAM necessary to
> >>>> even boot FreeBSD.
> >>> Err, I thought we loaded PAE kernels at 2MB and non-PAE kernels at 4MB
> >>> to skip the first PSE page (PSE pages are 2MB on PAE).
> >> You are right, my mistake, sorry. In any case memory in the range
> >> 1MB-4MB can be used by default.
> > Errm, no it can't. PAE kernels (and amd64 kernels I think) are both
> > loaded at 2MB, so that only leaves memory in the range 1MB-2MB.
> I see, did not know about amd64 (PAE is less a concern for me since it's
> not a default kernel). What do you think about the following patch:
> It moves heap to the top of the extended memory and teaches
> i386_copyin() to avoid messing up this region, so that in low memory
> situation it will just fail, not trash heap.
So, if I understand correctly, you're now sticking the heap at the last 3MB of
RAM. FYI, as long as you have a PPro or newer you can test booting a PAE
kernel. You don't have to have > 4GB of RAM. So, you can test this locally
to see if you can boot a PAE kernel (bzipped at that!) before committing.
John Baldwin <jhb at FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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